1. Field of the Invention
The present invention is related to a system and method for handling broadcast-type service requests in a peer-to-peer ad-hoc wireless network. More particularly, the present invention is related to an improved system and method for handling Address Resolution Protocol (ARP) and Dynamic Host Configuration Protocol (DHCP) messages, among other broadcast-type messages, within the network stack of a local node in order to provide auto-configuration and discovery of Internet Protocol (IP) to Media Access Control (MAC) address mapping services in a peer-to-peer ad-hoc wireless network.
2. Description of the Related Art
In recent years, a type of mobile communications network known as an xe2x80x9cad-hocxe2x80x9d network has been developed. In this type of network, each user terminal (hereinafter xe2x80x9cmobile nodexe2x80x9d) is capable of operating as a base station or router for the remaining mobile nodes, thus eliminating the need for a fixed infrastructure of base stations. Accordingly, data packets being sent from a source node to a destination node are typically routed through a number of intermediate mobile nodes before reaching the destination node. Details of such ad-hoc networks are set forth in U.S. Pat. No. 5,943,322 to Mayor, the entire content of which is incorporated herein by reference.
More sophisticated ad-hoc networks are also being developed which, in addition to enabling mobile nodes to communicate with each other as in a conventional ad-hoc network, further enable the mobile nodes to access a fixed network and thus communicate with other types of user terminals, such as those on the public switched telephone network (PSTN) and on other networks, such as the Internet. Details of these types of ad-hoc networks are described in U.S. patent application Ser. No. 09/897,790 entitled xe2x80x9cAd Hoc Peer-to-Peer Mobile Radio Access System Interfaced to the PSTN and Cellular Networksxe2x80x9d, filed on Jun. 29, 2001, in U.S. patent application Ser. No. 09/815,157 entitled xe2x80x9cTime Division Protocol for an Ad-Hoc, Peer-to-Peer Radio Network Having Coordinating Channel Access to Shared Parallel Data Channels with Separate Reservation Channelxe2x80x9d, filed on Mar. 22, 2001, and in U.S. patent application Ser. No. 09/815,164 entitled xe2x80x9cPrioritized-Routing for an Ad-Hoc, Peer-to-Peer, Mobile Radio Access Systemxe2x80x9d, filed on Mar. 22, 2001, the entire content of each of said patent applications being incorporated herein by reference.
Generally, all nodes present in a wireless ad-hoc peer-to-peer network provide similar services and functionality. These networks therefore distinguish themselves from infrastructure networks where one or more nodes offer a superset of the functionality of the remaining network. These infrastructure nodes in such networks typically can handle Dynamic Host Configuration Protocol (DHCP), Address Resolution Protocol (ARP), as well as other services that depend on broadcast traffic. Protocols, such as DHCP, are defined by IETF RFC 2131 and 2132, and are used by a client node to automatically obtain network settings from a central server. These network settings include the client""s IP address, the address of Domain Name Servers (DNS), the IP address of default gateways, and numerous other network settings. Additional protocols, such as ARP, are defined by STD 0037 and RFC 0826, and are used by a network node to map IP addresses to MAC addresses so IP traffic can be delivered to specific hardware.
These infrastructure nodes are normally discovered by broadcast traffic advertisements from their client nodes in a network. However, as known to those skilled in the art, peer-to-peer networks typically do not contain specialized infrastructure nodes. In response to the advanced network configurations, the IEEE 802.11 standard offers a peer-to-peer mode in addition to an infrastructure mode. Details of the 802.11 standards are set forth in ISO/IEC 8802-11, ANSI/IEEE 802.11 xe2x80x9cInformation Technologyxe2x80x94Telecommunications and Information Exchange Between Systemsxe2x80x94Local and Metropolitan Area Network Specific Requirementsxe2x80x9d, Part 11: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications, the entire contents of which being incorporated herein by reference. Also, a description of the 802.11 standard is presented in a text by Bob O""Hara and Al Petrick entitled xe2x80x9cIEEE 802.11 Handbook: A Designer""s Companion, IEEExe2x80x9d, 1999, the entire contents of which being incorporated herein by reference.
There are difficulties to broadcast traffic capabilities encountered in either network. For example, wireless ad-hoc routing networks typically avoid repeating broadcast traffic in an effort to avoid xe2x80x9cbroadcast stormsxe2x80x9d that can flood the transmission medium with traffic and cripple the ability of the network to deliver traffic. Broadcast traffic reception is usually limited to nodes in the immediate listening area of the transmitting node. Since ARP and DHCP depend on broadcast traffic, ad-hoc routing networks sometimes xe2x80x9ctunnelxe2x80x9d this broadcast traffic in directed packets to known infrastructure nodes where it can be handled. Traditional non-ad-hoc networks do not encounter the broadcast problem because their nodes communicate directly with each other. As noted, however, wireless peer-to-peer ad-hoc routing networks do not contain infrastructure nodes and therefore do not have the option to tunnel their broadcast traffic. Protocol communications, such as DHCP, ARP, and other broadcast network protocols must be handled in another way.
Accordingly, a need exists for an improved system and method for handling DHCP and ARP requests, as well as other types of requests which require broadcast traffic, in a peer-to-peer ad-hoc wireless network. A further need exists for handling broadcast-type requests in a network not having infrastructure nodes having a superset of functionality without generating unnecessary broadcast traffic.
An object of the present invention is to provide a system and method to determine a Media Access Control address for a node, and apply a hashing function to reduce the address to a two byte appendix to a subnet Internet Protocol address.
Another object of the present invention is to provide a system and method to communicate as a routing advertisement, an address for a node containing both Media Access Control address information and sufficient Internet Protocol address information to enable address mapping of the nodes.
Still another object of the present invention is to provide a system and method to maintain routing advertisements in a local ad-hoc routing table, and apply the address mapping information stored therein to answer locally generated requests, including ARP and DHCP requests.
These and other objects are substantially achieved by providing ad-hoc routing networks with the ability to auto-configure and discover Internet Protocol address to Media Access Control mappings, and gateway presence, in wireless peer-to-peer ad-hoc networks. More particularly, the present invention provides a system and method for handling ARP and DHCP messages, among other broadcast-type messages, within the network stack of a local node in order to provide auto-configuration and discovery of IP to MAC address mapping services in a peer-to-peer ad-hoc wireless network.
The system and method determines a Media Access Control address for nodes of a network, which is identified by a subnet Internet Protocol address, and applies a hashing function to produce an abbreviated Media Access Control address. An Internet Protocol address is constructed based on the abbreviated Media Access Control address and the subnet Internet Protocol address, and is communicated as a routing advertisement.
Receiving nodes maintain a local ad-hoc routing table based on the routing advertisement and apply maintained data to locally. The maintained data is used to answer intercepted ARP and DHCP requests at the node which no longer require transmission, thereby reducing overhead transmission levels in the network.